1. Field
The present disclosure relates to a flow regulator for an ambulatory infusion pump.
2. Discussion of Related Technology
Ambulatory infusion pumps allow hospital patients to remain mobile without having to carry a pole holding intravenous (IV) therapy devices. There is a growing demand for home IV therapy using disposable ambulatory pumps. Disposable ambulatory pumps, most of which are mechanical ambulatory pumps, have a characteristic flow pattern: the flow-rate is higher at the beginning and decreases throughout the life of infusion due to the decrease in the volume, and therefore pressure, of the drug reservoir. Thus, the precision of flow of disposable infusion pumps is typically in the range of ±15% to ±20%, which is significantly worse than that (±5% to ±8%) of electronic infusion pumps.
The advantages of disposable infusion pumps are their light weight, small size, simplicity of use, independence from an external power supply, elimination of programming errors, low initial cost, quiet operation, and disposability. Disadvantages include the possibility of inaccurate flow rates, fixed reservoir volume, lack of facility to change the flow rate and bolus-dose volume to provide adequate analgesia, inability to trace the history of the analgesia demand by the patient, and long-term cost.
There are several types of disposable infusion pumps, such as elastomeric, positive pressure (spring-powered or gas-pressure-powered), negative pressure (vacuum), and patient control analgesia (PCA) pumps. The accuracy of each pump's flow rate is dependent on several factors, including temperature, fluid viscosity, atmospheric pressure, back pressure, partial filling, and storage. Nonelectric disposable pumps may utilize a mechanical restrictor within the flow path to determine the speed of pressurized fluid. The preset flow rate of each device is mainly determined by the dimensions of the flow restrictor and the pressure supplied by the pressure source, for instance, a stretched elastomeric reservoir. The configuration of the stretched elastomeric reservoir offers the advantages of simplicity and convenience, which has resulted in wide acceptance of the device by the marketplace. However, certain limitations remain; one of them is variability of the flow rate due to changes in the upstream pressure provided by the elastomeric balloon (or other pressure generation means).
The foregoing discussion in this section is to provide general background information, and does not constitute an admission of prior art.